This proposal examines the potential of using an insect model for assessing environmental toxicity to vertebrates from chronic exposures to cyanide, arsenic and mercury, and to demonstrate that results obtained using model insect species are comparable, hence, applicable to studies of chronic toxicity and impact on the environment. Fundamental processes of toxicities of cyanide, arsenic and mercury are different, but each toxicant has a similar mode of action in almost all aerobic organisms. Literature supports our contention that these toxicants under chronic situation will induce oxidative stress by generation of activated forms of oxygen, inducing life-threatening lipid peroxidation and other deleterious effects on cellular processes. Oxidative stress is a chain-event, and a single initiating event caused by a prooxidant may cascade into a widespread chain reaction that produces many deleterious products in concentrations many magnitudes greater than the initiator. Thus, the proposed research is specifically aimed at assessing oxidative stress from chronic exposures of these three toxicants to larvae of a phytophagous insect species, the cabbage looper (Trichoplusia ni), and adults of a non-phytophagous species, the common housefly (Musca domestica). These studies will shed light on the degree that chronic exposures to toxicants causes oxidative stress, which, in turn, will enable us to determine the extent oxidative stress may be a significant factor in chronic exposure and toxicity.